Contractible boring head for mining machines



May 15, 1956 H. E. SMITH CONTRACTIBLE BORING HEAD FOR MINING MACHINES 2 Sheets-Sheet l Filed Dec. 16. 1954 INVENTOR. Herman E. Smih ATTORNEY May 15, 1956 H E, SMH-H 2,745,650

CONTRACTIBLE BORING HEAD FOR MINING MACHINES Filed DEG. 16, 1954 2 Sheets-Sheet 2 wl I kW/J (FL- 37 3a Fig, 2

INVENTOR.

Herman E. Smith BY 'l'.fH J

ATTORNEY Patented May l5, 1956 CONTRACTIBLE BORING HEAD FOR MINNG MACHlNES Herman E. Smith, Park Forest, Ill., assignor to Goodman Nalrlillflacturing Company, Chicago, Ill., a corporan'on o ois Application December 16, 1954, Serial No. 475,649

3 Claims. (Cl. 262-7) This invention relates to improvements in mobile min- -ing machines of the boring type wherein one or more ro- -tary boring heads, having a plurality of radial `cutter carrying arms, are forced into a face of standing mineral such as coal. Such machines are commonly provided with means for reducing the outer diameter of the boring heads to aid in permitting the machine as a whole to be withdrawn from the bore yand transported from place to place in the mine.

Certain means previously devised for collapsing the outer ends of the radial arms of the boring head are disclosed in copending applications Serial Nos. 431,454 and 463,867 filed, respectively, on May 2l, 1954, and October 22, 1954, owned by the assignee of `the present invention, which means consist broadly in hinging the arms on the boring head hub so that they may be swung toward and away from the axis of the boring head. This type of hinged arm structure presents diicult problems in providing eicient and compact mechanism for swinging lthe arms simultaneously and -at the same time enclosing and sealing the critical bearing surfaces of said mechanism against ingress of dirt, grit or the like, which bearing surfaces otherwise might be exposed to abrasion and corrosion so as to interfere with the efficient operation of the mechanism.

The principal object of the present invention lis to provide an improved, simplified and more efficient boring head structure of the character above mentioned, wherein the varm-swinging mechanism is of simpler and more compact construction and eliminates the requirement `for yspecial enclosing and sealing means f-or the critical lbearing surfaces of the arm-swinging mechanism.

Other objects of the invention will appear as the following description proceeds.

The invention may best be understood by reference to the accompanying drawings, in which:

Figure l is a side view of a cutter head constructed in accordance with the present invention, showing the hinged arms in fully extended position and with certain parts shown in section.

`Figure 2 is a front view in part section of the cutter head shown in Figure 1.

Figure 3 is an enlarged section showing in greater detail a portion of the mechanism shown in Figure l.

Referring now to details of the embodiment of the invention shown in the drawings, the cutter head indicated generally at 20 has a hollow drive shaft 21 with a stationary hydraulic cylinder 22 mounted within the hub, having a piston rod 23 extending from its forward end axially of said shaft. A cylindrical lslide 24 is keyed as at 25' for longitudinal slidab'le movement Within the front end of the shaft 21. The slide 24 has an enlarged head 26 at Lits forward end carrying two pairs of diametrically opposed ears 27, 27 extending radially therefrom, each pair of said ears being pivotally connected -to a link 28.

The front end of the piston rod 23 is coupled to the head 26 of slide 24 by a rotating coupling 23a such as broadly disclosed in copending application ySerial No.

463,867 above-mentioned, to permit extension or retraction of the slide 24 by hydraulic power while it is rotating with the shaft 2l about the stationary hydraulic cylinder 22.

The cutter head has an elongated hub 29 fixed on the shaft 21 as by a spline 3i. Said hub may be further held in place by set screws 32 extending rearwardly from an inwardly projecting shoulder portion 29a at the front end of the hub, which ts against the front end of rthe shaft 21.

The hu'b 29 has two diametrically opposed `bosses 33, 33 extending radially of said hub at its front end yto provide pivotal support for the inner ends of the hinged boring arms 34, 34. in the form shown, each of said arms has a pair of ears 34a, '3fm at its inner end which forms a yoke embracing the adjacent lboss 33 on the hub 29, and hinged to said boss by a pivot pin 3S.

Each of the boring arms 3d has one or more cutter supports .34h suitably mounted on its front face and projecting forwardly therefrom. ln the form shown herein, the hub 29 also has a pair of integral short arms 26a projecting at `right :angles to the bosses '33 and carrying forwardly projecting cutter supports 26h lthereon for cutting a relatively small circular kerf.

Each of the arms is pivotally connected to one of the links 2S by a pivot pin 23o, disposed intermediate the front and rear longitudinal faces of i-ts respective farm on a transverse axis disposed outwardly of the bosses 33 on hub 29, as shown in Figures l and 2. Each of the bosses 33 has a slot 37 cut away at a forwardlyand inwardly inclined angle yto provide clearance for the ladjacent link 2S when the hinged arms are in their fully extended cutting position, as shown in full lines in Fgure l. The slots 37 are preferably of only slightly greater width than their respective links 28, so as to provide additional support for `the arms 34 against bending or twisting when the boring head is rotated during the `boring operation.

As will also be seen from Figures l and 2, the outer ends of each of the links 2S -t in a slot '3S extending forwardly and rearwardly of its respective arm to provide working clearance for said link said slot having a forwardly and outwardly inclined face 39 which forms a stop for engagement with its respective link to limit the forward swinging movement of the arm as will presently be described.

A tapered center breaker or Ileurs-ter cone 36 of convention-al form is suitably secured to the front face of the enlarged end 26 of the slide 24 vas by bolts 40, di).

An annular forwardly tapered rib d2 may be formed on the front face of the shouldered portion 25a at the front end of the hub adapted to fit in a mating groove d3 in the enlarged head 2e of slide 24?-, when the slide is in fully retracted position, as shown in full lines in Figure 1, so as to provide additional stability for the burster cone 36 in a centered relation relative to the hub. A sealing ring may be disposed around the inner periphery of vthe shouldered portion 29a in juxtaposition to the front end of the shaft 2i in position to engage the outer surface of the slide Zd yas the lat-ter is reciprocated in the shaft 21.

The use and operation is as follows:

During normal boring operations the radial boring arms 3d will be swung to their fully extended positions substantially perpendicular to the axis of the head, as shown in Figure l. ln this position the slide 24 is in its rearwardmost or fully retracted position in the hub 21, with its enlarged head 26 in abutting engagement with the front face of the hub 2l. When the head is thrust forwardly during the boring operation, reaction on the burster cone 36 will tend to urge the slide towara1 its rearwardmost position, aided, if necessary, by hy- V 3 `draulic pressure maintained in the cylinder 22. In this operating position it Will be observed that the longitudinal bearing surfaces of the slide will be fully retracted in the hub and enclosed by the head 26, so as to be fully sealed and protected against abrasion or erosion. It will further be noted from Figure 3 that with the arms in the extended boring position just mentioned, the annular tapered rib 42 on the hub will engage in the corresponding groove 43 in the head 26 to aord increased sealing effect for the bearing surf-aces of the slide, as well as to provide greater stability for the burster cone 36.

The hinged arms may 'be collapsed forwardly into a position so as to reduce the overall diameter of the bor- 'ing head when the entire boring head is retracted or withdrawn from the working face, as, for instance, if the machine is to be moved from place to place in the m-ine. This vcollapsing movement is ermtected by exerting hy draulic pressure on the piston rod 23 to thrust the slide 24 with its head 26 forwardly. This movement carries the two links 28 forwardly to an advanced position so as to swing the cutter arms 34 simultaneously on their hinged pins 3S into the forwardly inclined collapsed positions as indicated in dotted lines at the upper portion of Figure l. Such forward hinged movement of `t-he arms may be limited by suitable stop means, herein provided by the upper walls of the slots 39 against which the links 28 will be engaged at the forward limit of hinged movement of said arms, Ias will also be seen in Figure 1.

'It will be observed that by reason of the improved and `simplified arrangement of control linkage and slide of the present invention, it is possible to encompass all of lthis mechanism in an especially compact vrelation at the hub, particularly when the boring arms are in fully eX- tended position for boring operations. Moreover, the links 2S are disposed at forwardly inclined angles `to their respective cutter arms when `the latter 'are in fully eX- tended positions, so as to be placed under tens-ion to aid in supporting said arms when the head 26, to which said 4 links are connected, is engaged with the lfront end of `the hub.

Although I have shown and described certain embodiments of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described but that various changes and modications may be made without departing from the spirit and scope of the invention as defined by the appended'claims.

I claim:

l. In a boring head for mining machines, a rotatable hollow hub having a plurality of cutter arms hinged at its forward end for limited swinging movement in radially extending planes including the axis of said hub, :a slide reciprocably mounted lin the front end of said hollow hub having an enlarged head projecting beyond the front end of said hub, a link connecting the said enlarged head with each of said cutter ar-ms for swinging the latter simultaneously in response to rec-iprocable movement of said slide in said hub, said head being movable rearwardly to engage the front end of said hub and enclose the longitudinal bearing Vsurfaces of said 1slide in said hub when the cutter arms `are -in fully extending boring position.

2. The structure of .claim 1, wherein each of the links is inclined rearwardly and outwardly so that each link is placed under tension to support its respective arm against rearward swinging movement in its fully extended boring position.

3. The structure of claim 2, wherein the hub has rearwardly and outwardly inclined 4slots for receiving the intermediate portions of the 'links in close-fitting relation therein when the arms are in fully extended boring position.

References Cited in the file of this patent UNITED STATES PATENTS 

